Hydrofluorination of unsaturated organic compounds



Patented Feb. 22, 1949 HYDROFLUORINATION OF UNSATURATED ORGANIC COMPOUNDS John D. Cali'ee, Manhasset, and Francis H. Bratton, Floral Park, N. Y., assignora to Allied Chemical 8; Dye Corporation, a corporation of New York No Drawing. Application November 22, 1944, Serial No. 564,733

17 Claims. (01. 260-653) This invention relates to hydrofluorination of unsaturated organic compounds containing an aliphatic unsaturated linkage, i. e., an olefinic or an acetylenic linkage, particularly to hydrofiuorination of olefins and acetylenes.

The limited amount of work which has been carried out on hydrofiuorination of unsaturated compounds has demonstrated that this reaction proceeds with difflculty, poor yields of the desired fluorides generally being obtained. Thus, iii

non-catalytic hydrofluorination of olefines re-. quires employment of superatmospheric pressures and, in some instances, the use of low temperatures of the order of 25 to 60 C.;' United States Patent 1,996,115, issued to Lazier April 2,

1935, indicates that in the presence of zinc fluoride propylene may be reacted with hydrogen fluoride at a superatmospheric pressure of the order of 750 pounds per square inch and at a temperature of the order of 250 C. to produce a propyl fluoride. Both these types of reaction, however, are disadvantageous in that super-atmospheric pressures are required. Non-catalytic hydrofluorination of acetylenic compounds has also presented many difiiculties. "Organic Reactions, vol. 2, page 66 (1944), the reaction of acetylene with hydrogen fluoride is violent and uneven, since at low temperatures the reaction tends toward explosive violence, whereas at higher temperatures much resinification takes place; while the higher acetylenes may be hydrofluorinated more readily than acetylene, low temperatures of the order of 20 C. are generally required for satisfactory reaction.

It is an object of this invention to provide a novel process for hydrofluorinating unsaturated organic compounds containing an unsaturated aliphatic linkage.

It is a more particular object of this invention to provide a process for hydrofluorlnating olefins and acetylenes which may be carried out at atmospheric pressure and at temperatures in the neighborhood of room temperature, and

which is applicable to hydrofluorination of compounds heretofore regarded as difficult to hydrofiuorinate, such as acetylene and ethylene. In accordance with this invention hydrofluorination of unsaturated organic compounds con-' taining an unsaturated aliphatic linkage is car-' ried out by reacting the compound with hydrogen fluoride in the presence of fluosulfonic acid. The fluosulfonic acid, we have found, catalyzes addition of hydrogen fluoride to the unsaturated linkages of the compound being treated, so that 55 the hydrofiuorination proceeds smoothly to give good yields of the desired iiuqrides.- The process of our invention may be satisfactorily carried According to out at atmospheric pressure and at temperatures which may vary between -40 and +160 0.,

temperatures between about 20 and about C. being preferred; the process of our invention thus ofiers the practical advantage of permitting hydrofiuorination to be carried out at temperatures within the range 0 to 100 C. A particularly advantageous feature of our invention is that it permits hydrofluorination of acetylene to be carried out smoothly and without dlfilculty to form vinyl fluoride and 1,1-difiuoroethane. Ethylene also may be readily hydroiiuorin-ated in accordance with our invention to give ethyl fluoride. Furter the relatively inert vinyl fluoride may also be hydrofluorinated by the process of our invention to give 1,1-difluoroethane.

The compounds which may be treated in accordance with this invention may be any organic compound containing an unsaturated aliphatic or cycloaliphatic linkage, provided the compound is not excessively decomposed or polymerized upon contact with iiuosulfonic acid or hydrogen fluoride at the temperature at which hydroiiuorination is carried out. This will generally include all organic compounds containing unsaturation in aliphatic or cycloaliphatic portions thereof, provided such compounds do not contain conjugated unsaturated linkages (i. e. unsaturation in alternatecarbon to canbon linkages). Thus, aliphatic mono-olefins and unconjugated diolefins, cyclo-olefins, aromatic compounds substituted in the nucleus by an unsaturated aliphatic residue containing no double or triple bond in the position alpha to the aryl nucleus, acetylenes, unsaturated fatty acids, unsaturated aliphatic ethers and unsaturated aliphatic amines may be hydrofiuorinated in accordance with the process of our invention; these compounds may contain halogen or other inert sub-.

stituents in their structure. For example, ethylene, propylene, butylenes and other higher olefins, cyclohexene, vinyl chloride, vinyl fluoride, allyl benzene, acetylene and the higher acetylenes, oleic acid or 'stearolic acid may be hydrofluorinated in accordance with this invention anhydrous hydrogen fluoride and the mixture 1 passed through fiuosulfonic acid in a reaction vessel, which may be constructed of suitable resistant material such as iron, steeL'brass, Monel metal or stainless steel. The amount of hydrogen fluoride admixed with the compound to be 3 treated may vary somewhat, but generally the hydrogen fluoride is employed in amounts which are approximately stoichiometric for the desired reaction. The temperature at which the reaction is carried out may vary considerably, depending to some extent upon the unsaturated compound being treated, since the use of the fluosulfonic acid catalyst permits hydrofluorination to be catalyst. The pressure at which the reaction is carried out is preferably atmospheric pressure, but superatmospheric pressures may be employed if desired. The reactions may be carried out continuously or batchwise; a desirable method for hydrofluorinating acetylenes or oleflns in accordance with the invention involves passing a mixture of the acetylene o'r olefin and hydrogen fluoride through a series of reactors containing fluosulfonic acid in order to insure complete conversion of the acetylene or olefln to the hydrofluoride, the last reactor being maintained at a temperature below C. to absorb any unreacted hydrogen fluoride in the gas.

If the compound to be hydrofiuorinated is a liquid, such as an amylene, or a solid such as stearolic acid, it is preferably mixed with fluosulfonic acid, and hydrogen fluoride then passed into the mixture under the conditions above described.

A preferred embodiment of our invention in- 'volves hydrofluorination of acetylene, since we have found this reaction may readily be carried out under the conditions above specified to form vinyl fluoride and 1,1-difluoroethane. In the production of 1,1-difluoroethane from acetylene, if desired, a portion of the reaction product may be refluxed in the reaction vessel to assist in attaining substantially complete conversion to the difluoride. Production of substantial amounts of vinyl fluoride may be realized by passage of a substantially equimolar mixture of acetylene and hydrogen fluoride into the fluosulfonic acid with no partial reflux, whereby a product containing vinyl fluoride in admixture with smaller amounts of 1,1-difluoroethane is obtained.

In accordance with another preferred embodiment of our invention, hydrofluorination of vinyl halides, such as vinyl fluoride, may be accomplished by passing the vinyl halide in admixture with hydrogen fluoride through fluosulionic acid. Since vinyl fluoride is a relatively inert compound and hitherto has been extremely diflicult to hydrofluorinate, it is evident the process of our invention possesses important advantages over prior processes for carrying out hydrofluorination reactions.

Still another preferred embodiment of our invention involves hydrofluorination of ethylene, a reaction which heretofore has been carried out only with extreme difliculty. We have found that by passing a substantially equimolar mixture of ethylene and hydrogen fluoride into fluosulfonic acid at about room temperature, ethyl'fluorlde aeaaace 4 may be obtained in yields amounting to 60% and more.

It is to be understood that since hydrogen fluoride and sulfur trioxide react instantaneously to form fluosulfonic acid, the process of our invention may also be carried out by contacting hydrogen fluoride with a mixture of the compound to be hydrofluorinated and sulfur trioxide. or by contacting sulfur trioxide with a mixture of hydrogen fluoride and the compound to be hydrofluorinated; further, if desired, sulfur trioxide, hydrogen fluoride and the compound to be hydrofluorinated may be mixed in the gas phase, whereby fluosulionic acid condenses and acts as the catalyst. I The following examples are illustrative of our invention. Amounts are given in parts by weight.

Example 1 35 parts of fluosulfonic acid were placed in an iron reactor packed with steel wool and about 15 parts of hydrogen fluoride were then introduced, the temperature being maintained at 0 C. A mixture of vinyl fluoride and hydrogen fluoride, the mol ratio of vinyl fluoride to hydrogen fluoride being essentially equimolar, was then passed through the fluosulfonic acid at a rate of about mol per hour, the temperature of the reactor being permitted to rise to about 25 C. during the course of the reaction. The gaseous productsof the reaction were passed through a tube packed with sodium fluoride to remove excess hydrogen fluoride therefrom and then through a condenser maintained at 50 0.; 1,1 difluoroethane was recovered by fractionation of the condensate, the per cent yield, based on the vinyl fluoride, being about Example 2 44 parts of fluosulfonic acid were placed in an iron reactor packed with steel wool and about 15 parts of hydrogen fluoride were then introduced, the temperature being maintained at 0 C. A mixture of ethylene and hydrogen fluoride in substantially equimolar quantities was then passed through the fluosulfonic acid at a rate of about A mol of ethylene per hour, the temperature of the reactor being permitted to rise to about 25 C. during the course of the reaction. The gaseous products of the reaction were passed through a tube of sodium fluoride to remove excess hydrogen fluoride and then through a condenser maintained at 78 C. Ethyl fluoride was obtained by fractionation of the condensate, the per cent yield, based on the ethylene, being about 60%.

Example 3 570 parts of fluosulfonic acid and about 50 parts of hydrogen fluoride were placed in a steel reactor provided with a reflux condenser. Acetylene and hydrogen fluoride, the mol ratio of acetylene to hydrogen fluoride being 1:2, were then passed through the fluosulfonic acid at a rate of about 1.5 to 2 mols of acetylene per hour, the temperature of the reactor being maintained at about 0 C. and the reflux condenser being held at -25 C. The reaction products were passed through sodium fluoride to remove excess hydrogen fluoride. By operating in this-manner practically complete conversion of acetylene to 1,1-difluoroethane was attained.

Example 4 parts of fluosulfonic acid were placed in an iron reactor maintained at a temperature of v 80 to 90C. by means of an oil bath. A mixture of acetylene and hydrogen fluoride in a molar ratio of 1:2 was then passed through the fluorosulfonic acid at a rate of about 1 mole of acetylene per hour, the gaseous products of reaction after passing over sodium fluoride to remove unreacted hydrogen fluoride, were condensed at -78 C. The reaction was carried on for about 1 hours. 85 parts of condensate were thus obtained; the condensate analyzed approximately by weight of acetylene, 50% by weight of vinyl fluoride and40% by weight of ethylidine fluoride.

fluosulfonic acid.

2. In the hydrofluorination of unconjugated unsaturated aliphatic compounds, the improvement which comprises reacting hydrogen fluoride with the unsaturated aliphatic compound in the presence of fluosulfonic acid at substantially atmospheric pressure.

3. In the hydrofluorination of unconjugated,

unsaturated aliphatic compounds, the improvement which comprises reacting hydrogen fluoride with. the organic compound in the presence of fluosulfonic acid at substantially atmospheric pressure and at a temperature between about and about +160 C.

4. A continuous process for the hydrofluorination of unconjugated unsaturated aliphatic compounds, which comprises continuously passing a gaseous mixture of hydrogen fluoride and the unsaturated aliphatic compound through fiuosulfonic acid at substantially atmospheric pressure.

5. A process for the hydrofluorination 0 mixture of acetylene and hydrogen fluoride through fluosulfonic acid.

6. A process for the production of 1,1-difluoro ethane by the hydrofluorination of acetylene, which comprises passing a gaseous mixture of acetylene and hydrogen fluoride, in which the mol'ratio'ot hydrogen fluoride to acetylene is about 2:1, through fluosulfonic acid at substantially atmospheric pressure and at a temperature between about 40 and about +160 C.

7. A process for the production of ethyl fluoride by the hydrofluorination of ethylene, which comprises passing a gaseous mixture of ethylene and hydrogen fluoride through fluosulfonic acid.

8. A process for production of ethyl fluoride by the hydrofluorination of ethylene, which comprises passing a gaseous mixture of ethylene and hydrogen fluoride. in which the mol ratio of ethylene to hydrogen fluoride is about 1:1, through fluosulionic acid substantially at atmospheric pressure and at a temperature between about -40 and about +160 C.

9. A process for the production of 1,1-difluoroethane by the hydrofluorination or vinyl fluoride, which comprises passing a gaseous mixture of vinyl fluoride and hydrogen fluoride through 10. A process for production of 1,1-difluoroacetylene, which comprises passing a gaseous 6 ethane by the hydrofluorination of vinyl fluoride. which comprises passing a gaseous mixture of vinyl fluoride and hydrogen, fluoride, in which,

the mol ratio of vinyl fluoride to hydrogen fluoride is about 1:1, through fiuosulfonic acid at substantially atmospheric pressure and at a temperature between about 40 and about +160 C.

11. A process for the hydrofluorination of unconjugated, unsaturated aliphatic compounds. which comprises passing a mixture of said organic compound and anhydrous hydrogen fluoride into a reaction medium consisting essentially of fluosulfonic acid at substantially atmospheric pressure and at a temperature between about -20 and about C.

12. In the hydrofluorination of unsaturated aliphatic compounds containing not more than two carbon atoms, the improvement which comprises reacting hydrogen fluoride with the organic compound in the presence of fluosulfonic acid.

13. In the hydrofluorination of unsaturated aliphatic compounds containing not more than two carbon atoms, the improvement which comprises reacting hydrogen fluoride with the organic compound in the presence of fluosulfonic acid at substantially atmospheric pressure.

14. In the hydrofluorination of unsaturated aliphatic compounds containing not more than two carbon atoms, the improvement which comprises reacting hydrogen fluoride with the organic compound in the presence of fluosulfonic acid at a temperature between about --40 and about C.

15. A process for the hydrofluorination of an unsaturated aliphatic compound containing not more than two carbon atoms, which comprises passing a mixture of said compound and hydrogen fluoride into fluosulfonic acid at substantially atmospheric pressure and at a temperature between about 40 and about +160 C.

16. A process for the hydrofluorination oi acetylene, which comprises passing a gaseous mixture of acetylene and hydrogen fluoride through fluosulfonic acid at substantially atmospheric pressure. i

17. A process for the hydrofluorination or acetylene, which comprises passing a gaseous mixture of acetylene and hydrogen fluoride through fluosulfonic acid at substantially atmospheric pressure and at temperature between about --40 and about.+160 C.

JOHN D. CALFEE. FRANCIS H. BRATTON.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 2,062,743 Dandt et a1. Dec. 1, 1936 2,090,772 Wiezevich Aug. 24, 1937 FOREHGN PATENTS Country Date Great Britain May 28, 1935 OTHER REFERENCES Number 

